Where does this come from, and can I check it?

Blood accounts for roughly seven to eight percent of total adult body weight. The figure is taken from MedlinePlus, which is linked in full on this page. Every fact on Mondo Knows names its source rather than repeating an unsourced claim.

Is this really a human body fact?

Yes. It sits on the Human Body shelf, one of 1,090 sourced facts grouped into space, animals, the human body, history, science and more. Category pages collect every fact in the same field.

What else can I read about it?

The links under the fact point to a quiz, game, puzzle or calculator on the same subject, and the shelf below shows related facts. The wording here is original, and quoted phrases are marked as quotations.

Mondo Knows Facts

An average adult body contains about five litres of blood

Blood accounts for roughly seven to eight percent of total adult body weight

An adult human typically circulates between 4.5 and 5.5 litres of blood, depending on body size and gender. This fluid carries oxygen, dissolved nutrients, hormones, and immune cells to tissues while removing metabolic waste products like carbon dioxide and urea.

Donating platelets at Swedish blood donation center April 2025 — R. Henrik Nilsson · CC BY 4.0 · licence · source

Where this comes from

MedlinePlus

Facts that can change over time are reviewed and updated. If something here looks wrong, Mondo would rather know than be confidently incorrect.

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Tags: blood, volume, circulation

An average adult body contains about five litres of blood: the short answers

Where does this come from, and can I check it?: Blood accounts for roughly seven to eight percent of total adult body weight. The figure is taken from MedlinePlus, which is linked in full on this page. Every fact on Mondo Knows names its source rather than repeating an unsourced claim.
Is this really a human body fact?: Yes. It sits on the Human Body shelf, one of 1,090 sourced facts grouped into space, animals, the human body, history, science and more. Category pages collect every fact in the same field.
What else can I read about it?: The links under the fact point to a quiz, game, puzzle or calculator on the same subject, and the shelf below shows related facts. The wording here is original, and quoted phrases are marked as quotations.